Robotic laser pointer apparatus and methods

ABSTRACT

A robotic laser-pointing apparatus has an instrument center, a first rotation axis, a second rotation axis, and a pointing axis, with the first rotation axis, the second rotation axis and the pointing axis in a known relationship to the instrument center. A laser source provides a pointing-laser beam along the pointing axis. A pointing drive system aims the laser beam by rotating the pointing axis about the instrument center in response to a pointing-direction control. Focusing optics having a focusing-optics drive serve to focus the pointing-laser beam in response to a focusing-optics control. A processor, responsive to target-position information, generates the pointing-direction control and the focusing-optics control. Some embodiments include an electronic-distance-measurement system having a measurement beam. Some embodiments provide for compensation of aiming errors of the pointing-laser beam and the measurement beam.

RELATED APPLICATIONS

The following patents and publications are related hereto and theircontent is incorporated herein by this reference: Provisionalapplication for U.S. Patent No. 61/722,168 filed 3 Nov. 2012; U.S. Pat.No. 7,441,340 B2 dated 28 Oct. 2008; U.S. Pat. No. 8,031,332 B2 dated 4Oct. 2011; and United States Patent Application Publication No.2012/0105870 A1 dated 3 May 2012.

BACKGROUND

Laying out mechanical, electrical and plumbing systems in new buildingsunder construction, or in existing buildings undergoing renovations oradditions, is tedious, time consuming, and expensive. Typically, it hasrequired a significant amount of labor to lay out construction points ata construction site on walls, ceilings and other surfaces, so that holescan be drilled and cuts made to permit the passage of pipes, conduitsand the like, and to permit the installation of hangers, switches,fittings and other items. This layout process has required teams ofworkers that measure and mark the locations of these constructionpoints, with much of the work being accomplished manually.

Manually measuring and accounting for all of these variables to locateconstruction points on walls and other vertical surfaces is difficultand time consuming. This process is subject to measurement errors and toaccumulated errors which compound as successive measurements are madegoing from one intermediate point to the next. Further, building designsand requirements have become more complex, and construction scheduleshave become tighter, adding to the need to facilitate and simplify thelayout process.

Robotic total stations are sometimes used for this purpose. For example,U.S. Pat. No. 8,031,332 B2 describes an iterative process usingconstruction data with a robotic total station to direct a beam of laserlight and establish a construction point.

A total station positioned at a known location directs a beam of laserlight toward a target (e.g., an object or object point or constructionpoint). By measuring the time of flight of the beam, the distancebetween the total station and the target is determined. By alsomeasuring the direction of the beam from the total station to thetarget, i.e., the altitude and azimuth angles that define a vector fromthe total station to the target, the location of the target can beprecisely determined.

Robotic or automated total stations are capable of locating an objectpoint without being attended by an operator. Such total stations can becontrolled to point in precisely determined directions. A total stationcan point to surfaces throughout a worksite and, by detecting the lightreflected from those surfaces, determine the three-dimensionalcoordinates of the illuminated points throughout the worksite inrelation to the position of the total station. If the coordinates andthe orientation of the total station are known, the coordinates of theilluminated points are also known.

Robotic total stations are known to make distance and anglemeasurements, compute the location of the robotic total station relativeto reference points, and then use the robotic total station's reddistance-measurement laser as a pointer for layout of constructionpoints. Trimble Navigation Limited provides such laser-pointer layoutfunctionality in its field software products “Trimble MEP” and “TrimbleField Link for MEP” which are offered with its robotic total stationmodels RTS555, RTS655, RTS633, RTS773 and other instruments. While theserepresent a significant advance over prior products, furtherimprovements are desirable.

Using the red distance-measurement laser of a robotic total station as apointer, e.g., for construction layout, has a number of drawbacks.First, the wavelength of the red laser makes it difficult for the humaneye to see a spot projected on a target under daylight conditions. FIG.1 shows the luminosity (human color perception) of light as a functionof wavelength. For example, the luminosity of a typical red laser of 650nm wavelength is about 0.1 in daylight and is effectively zero at night.

Second, the electronic-distance-measurement (EDM) optics are not wellsuited for use as a pointer. Visible-laser EDM optics have smallaperture for the transmitted beam to separate the transmission path fromthe reception path and avoid coupling transmitted and received light.The EDM of a typical total station has coaxial paths for the transmittedbeam and capture of light reflected from a target surface. Thetransmitted beam passes through a small center aperture, while the lightreflected from the target returns through a much larger aperture havingits central region blocked by the center aperture of thetransmitted-beam path.

FIG. 2 schematically illustrates at 200 the optics of such a totalstation. A first optical path, which allows a user to view a target, isdefied by an eyepiece 205 with reticle 210 and prism 215, a focusinglens 220 and a front lens 225. Focusing lens 220 is adjusted by amotorized focusing drive 230. The EDM laser beam 240 enters from theside and is deflected by a transmitter prism 245 to exit as asmall-diameter beam through front lens 225 along optical path 250. Light255 received along optical path 250 enters over the full aperture offront lens 225 and is shadowed at the center by the small-diametertransmitter prism 245. Received light is reflected by mirror 265 along apath 270 to an EDM detector (not shown). Mirror 275 reflects light alonga path 280 to a target-tracking detector.

The transmitted laser beam travels in a straight direction, but has adivergence: its diameter increases with distance. The divergence is afunction of the diameter of the laser beam at the lens that focuses orcollimates the laser. That effect is called diffraction. The basicformula for the diffraction-related divergence angle is:

${\sin\;\alpha} = \frac{1,{22 \cdot \lambda}}{D}$where α is the half divergence angle of the beam to its firstdiffraction minimum and A is the wavelength and D is the diameter of thelimiting optics. Thus, the divergence of a laser is larger if thediameter that the laser uses at the optics is smaller. Typicaldivergence angles α are 0.1 to 0.2 mrad. This results in spot diametersof 10 mm to 20 mm at 50 m distance.

If the pointing beam is at a small angle (e.g., 20 deg) to the wall orceiling, the laser spot width increases in one direction by a factor ofthree in that case. At the same time the visibility decreases by afactor of three. Thus a laser spot that is wide has very poorvisibility, reducing precision of the layout task. Many operatorscompensate by using shorter distances and a larger angle to thewall/ceiling. Limiting the use cases to shorter distances and largeangles needs more set-ups of the instrument per working area.

The divergence angle due to the small center aperture and fixed opticsof the transmitted EDM laser beam means that the diameter of a spotprojected on a surface increases significantly with distance from therobotic total station.

FIG. 3 schematically illustrates at 300 a layout scenario using a totalstation 305 to layout a point on a ceiling 310 using the EDM laser beam315 to produce an unfocused laser pointer spot. The angle beta betweenthe ceiling 310 and the beam 315 is shown at 325. A beam of width d_bshown at 320 produces a spot of width d_w shown at 330 according to therelationd _(—) w=d _(—) b/sin(beta)so that d_w≈3·d_b for beta=20 deg and d_w≈6·d_b for beta=9 deg.

FIG. 5A shows an example of a laser spot of size 5 having a brightnesslevel 1. FIG. 5B shows an example of a laser spot of size 1 having abrightness level of 25. Laser power is limited by the laser class, e.g.,a Class 2 laser has a 1 mW limit. A laser spot of 10 mm diameter has anarea of 100 square mm, while a laser spot of 2 mm diameter has an areaof 4 square mm. Thus the same laser produces a spot which is 25 times(100/4) brighter at 2 mm diameter than at 10 mm diameter, and is morevisible even with lower laser power.

The user is thus tasked with identifying the projected red laser spot,whose color has low luminosity and whose diameter varies greatly withdistance from the total station, and then tasked with visuallyestimating the center of the projected spot as the desired constructionpoint.

A proposed solution to pointing with non-robotic theodolites is toremove the eyepiece of the theodolite telescope and replace it with apointing laser. The pointing laser uses the optical path otherwiseprovided for the user to manually aim the telescope at a target. Oneexample is the SwissTek Kern laser eyepiece having a green pointinglaser whose dot size can be manually focused. A similareyepiece-replacement solution, for industrial total stations, is theLeica DL2 Diode Laser Pointer having a red laser. A disadvantage ofthese manually-focused laser pointers is that the spot size at a givenfocus setting varies with distance from the instrument, so that toadjust the spot size requires manually resetting the laser focus foreach measurement range during a layout project.

The Pentax R-300X series instruments have user-selectable lasers andprismless auto focus which focuses the EDM laser to get signal return atshort range. A laser-pointer function turns the laser beam oncontinuously to become the aiming point for visual confirmation. Thelaser beam is designed not to be able to observe through the telescope.The user is instructed to visually align the laser beam to the targetand mark the center. The user is instructed to confirm the horizontaland vertical alignment before measuring when performing accurate worklike stake out when using the laser pointer function. The Pentax R-300Xseries instruments are not robotic, and thus not suitable for automatedpointing. Thus, the user stands behind the instrument. In contrast, witha robotic instrument the user is at the target location to mark theconstruction point.

Another instrument, the Leica Disto 3D robotic pointer, lacks focusingof the laser pointer and thus has the issues of spot size and brightnessdiscussed above.

Another instrument, the Trimble GX scanner, uses a focusable green laserfor high-speed scanning of points, but is a different class ofinstrument unsuited to construction layout applications.

Improved apparatus and methods are desired.

SUMMARY

Some embodiments in accordance with the invention provide a roboticlaser-pointing apparatus having an instrument center, a first rotationaxis, a second rotation axis, and a pointing axis, with the firstrotation axis, the second rotation axis and the pointing axis in a knownrelationship to the instrument center. A laser source provides apointing-laser beam along the pointing axis. A pointing drive systemaims the laser beam by rotating the pointing axis about the instrumentcenter in response to a pointing-direction control. Focusing opticshaving a focusing-optics drive serve to focus the pointing-laser beam inresponse to a focusing-optics control. A processor, responsive totarget-position information, generates the pointing-direction controland the focusing-optics control.

Some embodiments include an electronic-distance-measurement systemhaving a measurement beam. Some embodiments provide for compensation ofaiming errors of the pointing-laser beam and the measurement beam.

Some embodiments provide a camera and display. In some embodiments thedisplay is a touch-screen which enables tap-and-move aiming. Someembodiments include a remote controller in communication with theprocessor via a data link for remote control of the apparatus. Someembodiments provide a touch-screen display in communication with theremote controller to enable viewing of a pointing-laser spot on a targetsurface and to enable tap-and-move aiming.

Some embodiments provide methods of operation of the apparatus forlayout of construction points. Some embodiments provide methods ofoperation of the apparatus for measuring construction points.

BRIEF DESCRIPTION

These and other features of some embodiments of the claimed inventionare illustrated in the drawing figures, in which:

FIG. 1 shows the luminosity (human color perception) of light as afunction of wavelength;

FIG. 2 schematically illustrates the optics of a typical total station;

FIG. 3 schematically illustrates a prior art layout scenario using anunfocused laser pointer;

FIG. 4 schematically illustrates a layout scenario using a focused laserpointer in accordance with some embodiments of the invention;

FIG. 5A shows a large laser beam spot;

FIG. 5B shows a small laser beam spot;

FIG. 6 schematically illustrates a front view of a robotic pointingapparatus in accordance with some embodiments of the invention;

FIG. 7 schematically illustrates a side view of the robotic pointingapparatus of FIG. 6;

FIG. 8 shows controllable focusing optics for a laser beam in accordancewith some embodiments of the invention;

FIG. 9A and FIG. 9B show a controllable focusing scheme for a laser beamin accordance with some embodiments of the invention;

FIG. 10 schematically illustrates the optics of a robotic total stationhaving a focusable laser pointer in accordance with some embodiments ofthe invention;

FIG. 11 shows a graph of focus position vs. distance to an object inaccordance with some embodiments of the invention;

FIG. 12A schematically illustrates a plane wave passing through anaperture;

FIG. 12B illustrates diffraction of the surface of water due to a planewave passing through an aperture;

FIG. 12C shows a graph of intensity distribution of a plane wave afterpassing through an aperture;

FIG. 12D shows in perspective view a simulation of intensity of a laserafter passing through a square aperture;

FIG. 12E shows a focused spot projected on a surface by a laser beamafter passing through a square aperture in accordance with someembodiments of the invention;

FIG. 13A schematically illustrates a laser beam passing through a lenshaving a prism at the center and focused in accordance with someembodiments of the invention;

FIG. 13B shows a focused spot of a laser beam projected on a surfaceafter passing through a lens having a prism at the center in accordancewith some embodiments of the invention;

FIG. 14A schematically illustrates a laser beam passing through a lenshaving a prism at the center and defocused in accordance with someembodiments of the invention;

FIG. 14B shows a defocused spot of a laser beam projected on a surfaceafter passing through a lens having a prism at the center in accordancewith some embodiments of the invention;

FIG. 15 is a schematic block diagram of an apparatus in accordance withsome embodiments of the invention;

FIG. 16A is a perspective rear view of a robotic total station inaccordance with some embodiments of the invention;

FIG. 16B is a perspective front view of a robotic total station inaccordance with some embodiments of the invention;

FIG. 17 illustrates electronic distance measurement with a robotic totalstation;

FIG. 18 illustrates layout with an unfocused laser pointer;

FIG. 19 illustrates layout with a focused laser pointer in accordancewith some embodiments of the invention;

FIG. 20 illustrates layout with a focused laser pointer in accordancewith some embodiments of the invention;

FIG. 21 illustrates a method of operating an apparatus to set out apoint in accordance with some embodiments of the invention; and

FIG. 22 illustrates a method of operating an apparatus to measure apoint in accordance with some embodiments of the invention.

DETAILED DESCRIPTION

FIG. 6 schematically illustrates at 600 front view of a robotic pointingapparatus 605 in accordance with some embodiments of the invention. Apointing device 610 having optics 615 is mounted on an alidade 620 forrotation about an axis 625 under control of a motorized drive 630.Alidade 620 is mounted on a base 635 for rotation about an axis 640under control of a motorized drive 645. Base part is supported on atribrach 650.

FIG. 7 schematically illustrates at 700 a side view of the roboticpointing apparatus 605 of FIG. 6. Pointing device 610 has a pointingaxis 705. Each of the pointing axis 705, the rotation axis 625 and therotation axis 640 may intersect one another, or not, and may intersectan instrument center 710, or not. The rotation axis 625 and the rotationaxis 640 may be mutually orthogonal, or not. While it is convenient tohave the pointing axis 705, the rotation axis 625 and the rotation axis640 intersect one another at the instrument center 710, in practice thisis difficult to achieve with high precision. Similarly, while it isconvenient to have the rotation axis 625 and the rotation axis 640substantially orthogonal to one another, this is also difficult toachieve with high precision. Schemes for compensation of these factorsare known in the art.

As shown in FIG. 7, pointing device 610 has a laser source 715 emittinga laser beam along pointing axis 705. Focusing optics 720 in the laserbeam path are adjusted by a focus controller 725 so that the laser spotsize can be controlled as a function of range.

FIG. 8 shows at 800 the controllable focusing optics for a laser beam inaccordance with some embodiments of the invention. In this example,focus controller 725 includes a motorized drive 725 for moving thefocusing lens 720 over a range 730 to adjust the laser spot sizeaccording to range of the target on which the laser spot is to beprojected.

FIG. 9A and FIG. 9B show at 900 and 950, respectively, a controllablefocusing scheme for a laser beam in accordance with some embodiments ofthe invention. In this example, focus controller 725 includes amotorized drive 905 which focuses the laser beam by moving laser source715 relative to lens 615. FIG. 9A shows the laser beam focused for atarget at a longer range, while FIG. 9B shows the laser beam focused fora target at a shorter range.

FIG. 10 schematically illustrates at 1000 the optics of a robotic totalstation having a focusable laser pointer in accordance with someembodiments of the invention. A laser pointer optical path along opticalaxis 1045 is defined by a pointing-laser source 1015, a focusing lens1020, and a front lens 1005. Focusing lens 1020 is adjusted by amotorized focusing drive 1025. An EDM laser beam 1040 from ameasurement-laser source (not shown) enters from the side and isdeflected by a transmitter prism 1040 to exit as a small-diameter beamthrough front lens 1005 along optical axis 1045. Light received alongoptical axis 1045 enters over the full aperture of front lens 1005 (theextent of which is indicated by ray paths 1050 and 1055) except that itis shadowed at the center by the small-diameter transmitter prism 1040.Received light is reflected by mirror 1060 along a path 1065 to an EDMdetector (not shown). Optional mirror 1070 reflects light along a path1075 to an optional target-tracking detector (not shown). FIG. 11 showsat 1100 a graph of focus position vs. distance to an object inaccordance with some embodiments of the invention. The focus positionfor each distance to an object is given as a number of steps, e.g., ofmotorized focusing drive 1025. In some embodiments, these values arestored in a lookup table so that, when the distance to a target and thedesired spot size on the target are known, the corresponding value isretrieved from the lookup table and used to control the motorizedfocusing drive 1025.

Alternatively, focus position is calculated as needed when the distanceto a target and the desired spot size on the target are known. The focusposition as function of the distance is derived from formulas used forthe optics calculation. Because of production tolerances of the opticsand mechanics the focus position function further has at least onecalibration constant. That constant can be derived for example when thepointing laser spot is minimized in the manufacturing or by the user ata known distance. A mechanical alignment of the focusing optics at aknown distance could compensate for the tolerances.

Visually identifying the center of a laser-pointer spot on a target canbe difficult to do precisely. Accordingly, some embodiments of theinvention project a laser-pointer spot of a shape which facilitatesvisual identification of the center of the spot. In some embodiments thespot has intensity variations in the shape of crossed lines. In someembodiments the spot has concentric rings around a central region ofreduced brightness. In some embodiments the spot is modified by thediffraction of a positive or negative aperture to generate a pattern.

Since light is a wave, we apply wave theory. FIG. 12A schematicallyillustrates at 1200 a plane wave 1205 passing through an aperture 1210along an axis toward a plane 1220.

To show the diffraction principle, FIG. 12B illustrates at 1230 thediffraction of a water surface due to a plane wave passing through anaperture.

FIG. 12C shows at 1240 a graph of intensity distribution of a plane waveafter passing through an aperture. The central region 1245 is of highintensity, surrounded by smaller intensity peaks 1250, 1255, etc.

FIG. 12D shows at 1260 in perspective view a simulation of intensity ofa laser after passing through a square aperture. A central region 1265of high intensity is surrounded by two mutually-orthogonal lines oflower peaks, e.g., peaks 1270 and 1275.

FIG. 12E shows at 1280 a focused-laser spot projected on a surface by alaser beam after passing through a square aperture in accordance withsome embodiments of the invention. A central region 1285 of higherbrightness is at the center of two crossed lines of lower-intensitypeaks. Such a laser spot facilitates visual identification of the centerof a construction point.

FIG. 13A schematically illustrates at 1300 a laser beam from a source1305 passing through a lens 1310 having a square-shaped prism 1315 atits center, e.g., transmitter prism 1040 of FIG. 10 which creates ashadow zone 1320 at the center of the laser beam and acts as adiffraction pattern generator. When the laser spot is focused at therange of a target surface 1330, the square shape of the prism causesdiffraction perpendicular to the straight edges of the prism as in FIG.13B. The diffraction spreads a portion of the laser light in thevertical plane and in the horizontal plane. The effect can be seen as a“crosshair” around the spot.

FIG. 13B shows at 1350 a focused spot 1355 of a laser beam projected ona surface after passing through a lens having a square-shaped prism atthe center in accordance with some embodiments of the invention, e.g.,as in FIG. 13A. The scale is in millimeters. The spot has a centralregion 1360 of highest intensity, surrounded by rings of varyingintensity with smaller intensity peaks along mutually-orthogonal,crossed lines. In the image of FIG. 13B, lines 1365 and 1370 intersectwith lines 1375 and 1380 to provide for ready visual identification ofthe spot and of the spot center.

FIG. 14A schematically illustrates at 1400 a laser beam from source 1305passing through lens 1310 having square-shaped prism 1315 at its center,e.g., transmitter prism 1040 of FIG. 10 which creates a shadow zone 1320at the center of the laser beam and acts as a diffraction patterngenerator. In this example, the laser beam is defocusd at the range oftarget surface 1330 to from a laser spot on the target as in FIG. 14B.

FIG. 14B shows at 1405 a defocused spot 1455 of a laser beam projectedon a surface after passing through a lens having a square-shaped prismat the center in accordance with some embodiments of the invention,e.g., as in FIG. 14A. The scale is in millimeters. The spot has acentral region 1460 of lowest intensity, surrounded by rings 1465, 1470,etc. of varying intensity. In the image of FIG. 14B, the bullseye-likepattern of the laser spot provide for ready visual identification of thespot center. Thus when the spot is defocused it appears as a“shadow-image” of the exit aperture, which means that the blocked partof the light is visible as a darker area in the center of the spot.Since the dark portion is much smaller than the spot itself and appearsin the center of the spot, it can be used to mark a point moreaccurately than the spot size.

FIG. 15 shows at 1500 a schematic block diagram of an apparatus inaccordance with some embodiments of the invention. The apparatus has aninstrument center 1505, a first rotation axis 1510, a second rotationaxis 1515, and a pointing axis 1520. The first rotation axis 1510, thesecond rotation axis 1515, and the pointing axis 1520 have a knownrelationship to an instrument center. A laser source 1525 provides apointing-laser beam 1530 along the pointing axis 1520. A pointing drivesystem 1535 aims the laser beam by rotating the pointing axis 1520 aboutthe instrument center 1505 in response to a pointing-direction control1540. Focusing optics 1545 have a focusing-optics drive 1550 to focusthe pointing-laser beam 1520 in response to a focusing-optics control1555. A processor 1560, responsive to target-position information 1565,generates the pointing-direction control 1540 and focusing-opticscontrol 1555.

Each of the first rotation axis 1510, the second rotation axis 1515, andthe pointing axis 1520 may intersect with one or both of the others, ornot. Any or all of the first rotation axis 1510, the second rotationaxis 1515, and the pointing axis 1520 may intersect with the instrumentcenter 1505, or not. In some embodiments, at least two of the firstrotation axis 1510, the second rotation axis 1515, and the pointing axis1520 may intersect at the instrument center.

In some embodiments, the target-position information 1565 represents atarget location 1570 relative to the instrument center, and thepointing-direction control 1540 causes the pointing drive system 1535 toaim the pointing-laser beam 1530 at the target location 1570.

In some embodiments, the focusing-optics control 1555 causes thefocusing optics 1545 to focus the pointing-laser beam 1520 with apredetermined beam diameter at the target location 1570.

In some embodiments, the processor 1560 is operative to compute thefocusing-optics control 1555 based on range between the instrumentcenter 1505 and the target location 1570.

In some embodiments, the pointing drive system 1535 comprises a firstcontrollable drive 1575 for rotating the pointing axis 1520 to aselected rotation angle about the first rotation axis 1510, and a secondcontrollable drive 1580 for rotating the pointing axis 1520 to aselected rotation angle about the second rotation axis 1515. In someembodiments, the pointing-direction control 1540 comprises signalsrepresenting the selected rotation angles.

In some embodiments, the focusing optics system comprises at least oneoptical element and the focusing-optics drive 1550 is operative to focusthe pointing-laser beam 1530 by modifying at least one optical propertyof the focusing optics 1545. As illustrated in FIG. 9A and FIG. 9B,focusing can be done by moving the source with respect to the lenswithout changing the optical property of the optical element (e.g.,lens). Alternatively, or in addition to moving the source, an opticalproperty of the optical element is changed, e.g., the power of the lens(liquid lens) and/or distance between the lens and the source and/or thedistance between two optical elements.

To minimize divergence of the pointing-laser beam, the focusing opticssystem comprises a collimation lens having an exit aperture as large aspossible. In some embodiments, the exit aperture is at least 5 mm. Insome embodiments, the exit aperture is at least 10 mm. In someembodiments, the exit aperture is at least 20 mm. In some embodiments,the exit aperture is at least 30 mm.

In some embodiments, the processor 1560 is further operative tocompensate the pointing-direction control 1540 for any lack of mutualorthogonality of the first rotation axis 1510 and the second rotationaxis 1515. In some embodiments, the processor 1560 is further operativeto compensate the pointing-direction control 1540 for any lack of mutualorthogonality of the second rotation axis 1515 and the pointing axis1520.

Some embodiments in accordance with the invention further include anoptional electronic distance measurement system 1585 which is operativeto emit a measurement beam 1590 along a measurement-beam path 1595,e.g., when commanded by processor 1560. In some embodiments, themeasurement-beam path 1595 optionally intersects the instrument center1505.

In some embodiments, the processor 1560 is optionally further operativeto compensate the pointing-direction control 1535 for at least one ofparallax and divergence of the pointing axis 1520 with respect to themeasurement-beam path 1595.

In some embodiments, the electronic distance measurement system 1585comprises a measurement-beam source 1552, and the pointing-laser source1525 and the measurement-beam source 1552 are operated alternately.

In some embodiments, the pointing laser is green and the measurementbeam is red. When the red laser is active, the instrument is measuringand is not yet ready for layout. When the green laser is active, theinstrument is ready for layout. This offers a simple paradigm for theuser: red means “wait” and green means “go.”

In some embodiments, the processor controls the pointing-drive system tocorrect for misalignment between the measurement beam 1590 and thelaser-pointer beam 1530 when switching between them. This is done byhaving two sets of alignment corrections (collimation errors), one forthe laser pointer and one for the EDM, and switching between them whenswitching between laser pointer and EDM. This causes the pointing-drivesystem to re-aim so that the measurement beam 1590 and the laser-pointbeam 1530 will hit the same target location as the laser-pointer spotwas before the switch, e.g., target location 1570, and vice versa.

In some embodiments, the electronic distance measurement system 1585employs the pointing-laser source 1525 to generate the measurement beam1590.

In some embodiments, the pointing-laser beam 1530 is a class 2 laserbeam. In some embodiments, the pointing-laser beam 1530 has a wavelengthwithin a range visible to the human eye. In some embodiments, thepointing-laser beam 1530 has a wavelength of between 500 nm and 610 nm(day luminosity >50%, green to orange color). In some embodiments, thepointing-laser beam 1530 has a wavelength of between 450 nm and 550 nm(night luminosity >50%, blue to green color). In some embodiments, thepointing-laser beam 1530 has a wavelength of between 520 nm and 590 nm(day luminosity >80%, green to yellow color).

In some embodiments, the processor 1560 is operative to control thelaser source 1525 to set a power level of the pointing-laser beam 1530between a zero level and a maximum level.

Some embodiments in accordance with the invention further include anoptional camera 1554 operative to capture at least one of a still imageand a live video image of a target region. In some embodiments, thecamera has a field of view 1556 which encompasses a segment of thepointing axis 1520 for ranges of interest.

Some embodiments in accordance with the invention provide an optionaltouch-screen display 1558 which is operative to display an image of atarget region captured by the optional camera 1554. In some embodiments,the user can tap on the touch-screen display to indicate a targetlocation of interest and the processor is operative to control thepointing-drive system 1535 to aim the pointing axis 1520 at theindicated target location. In some embodiments, the camera is calibratedsuch that a pixel position in the camera image which corresponds to thelaser-pointer spot is calibrated for different distances between 1 m and100 m (to facilitate tap and move navigation using the camera image.)

In some embodiments, the user can then view the camera image of display1558 to aid in finding the laser-pointer spot at the target location1570. Many surfaces can look the same in a construction environment,making the laser-pointer spot difficult to find, such as 60 feet of wallsurface. By viewing the camera image, the user can look for a featurewhich will aid in finding the laser-pointer spot, such as a stack ofdrywall or the user himself in the camera image.

In some embodiments, the camera 1554 has an automatic exposure controlwhich indicates an exposure level, and the processor 1560 is operativeto use the exposure-level indication to adjust the power of thepointing-laser beam source 1525. In some embodiments, the power isreduced for longer camera exposure times. In some embodiments, the poweris increased for shorter camera exposure times.

Some embodiments in accordance with the invention further comprise anoptional data link 1562 between processor 1560 and an optionalcontroller 1564 remote from processor 1560. In some embodiments, thecontroller 1564 is operative to control the processor 1560 via the datalink 1562. Some embodiments further include an optional touch-screendisplay 1568 in communication with remote controller 1564, and theprocessor 1560 is operative to control the system in response tocommands entered on the display 1568, e.g., tap and move navigation asdescribed above with reference to display 1558. In some embodiments, acamera image is captured with the laser-pointer spot visible in thecamera image to document or prove the target location was correctlyidentified.

In accordance with some embodiments, the processor 1560 is operative todetermine a collimation-error correction between the pointing axis 1520and the measurement axis 1595. Techniques for error compensation areknown, for example, from U.S. Pat. No. 7,441,340 B2.

In accordance with some embodiments, the target position information1565 is retrieved from a physical storage medium. In some embodiments,the target position information 1565 is determined from a stored modelhaving a known relationship to the instrument center 1505. In someembodiments, the target position information 1565 is previously obtainedusing the EDM system 1585, which has a known relationship to theinstrument center 1505. In some embodiments, the target positioninformation 1565 is previously obtained using an EDM of anotherapparatus having a measurement center in a known relationship to theinstrument center 1505.

Trimble Navigation Limited plans to introduce new products embodyingmany of the inventive features described herein. These include theTrimble RTS873 robotic total station and the Trimble Field Tablet, whichwill provide layout solutions for MEP (Mechanical, Electrical andPlumbing) and Structures contractors with a version of the Trimble FieldLink software and a Surface module. Incorporating an auto-focus greenlaser, the new Trimble RTS873 Robotic Total Station will allow buildingconstruction contractors the ability to more easily collect and layoutfield points using robotic interaction.

The new Trimble Field Tablet with multi-touch gesture control willprovide a fluid, touch-based interface to 3D models and common layoutroutines within the Trimble Field Link software.

By interacting directly with the Trimble VISION® live video feed on theTrimble Field Tablet, contractors will be able to remotely view andmeasure field points within the Trimble Field Link software. This willallow contractors to move away from the total station, eliminating theneed for manual sighting of points to be measured. The auto-focus greenlaser pointer provides enhanced visibility and more accurate positioningwhen using Visual Layout with Trimble Field Link for MEP to lay outoverhead hangers or collecting as-built locations in bright daylightconditions.

The unique ability of the RTS873 robotic total station to focus thegreen laser at the defined measurement distance essentially eliminatesthe “laser spread” commonly seen with prior-art total station designs.

A complement to the new hardware, the Trimble Field Link softwarerunning on Trimble tablets will include the ability for contractors toview their design files in 3D (three dimension). This allows contractorsto create, select, and lay out points from a 3D view. Another newfeature in the software, Collect Floor Plan, offers the ability toautomatically collect a virtual footprint of a room using the totalstation to measure walls or interior facades. Perfect for adaptivere-use and renovation projects, the collected floor plan data can beused in conceptual design applications such as SketchUp to easily createa 3D design model for use by architects, engineers and buildingcontractors.

While the base features of Trimble Field Link software are the same forMEP, concrete, steel trades and general contractors, Trimble hasdeveloped a new module specifically for structures contractors. Idealfor concrete and general contractors, the new Surface module allows theuser to define a surface boundary and points by grid spacing or totalnumber of points to be collected. The surface can then be collectedmanually with a prism or automatically using Direct Reflex measurement.Once collected, the Trimble Field Link software can generate a reportthat will produce a color-coded topographical map of the surface showingenclosed high and low areas based on user defined reference elevationand tolerance. A report can be generated including the topographicrepresentation as well as areas and volumes of enclosed high and lowareas and percentage of surface defined as high, low, or in tolerance.

FIG. 16A is a perspective rear view 1600 and FIG. 16B is a perspectivefront view 1650 of the proposed RTS873 robotic total station embodyingsome of the inventive features described herein. The RTS 873 includes aremovable handle 1605, a 12V power connector 1610, a communicationconnector 1615, an on/off and trigger key 1620, a bottom instrumentheight mark 1625, screws 1655 for removing handle 1605, coaxial optics1660 for angle and distance measurements (tracker, red laser pointer andgreen laser pointers), camera optics 1665, face-2 display 1670, face-2keyboard 1675, internal battery compartment 1680, and antenna 1685.

FIG. 17 illustrates at 1700 electronic distance measurement with aprior-art robotic total station 1705. The measurement beam 1710 of theEDM has a fixed focus distance 1715 providing good visibility over thefunctional operating range of the total station. The EDM laser has asmall diameter (e.g., 5 mm) at the lens, increasing slightly withdistance (e.g., 10 mm at 20 m). This is normal laser behavior.

FIG. 18 illustrates at 1800 a layout operation with an unfocused laserpointer 1810 of a prior-art total station 1805. The spot size 1815 atthe target is not optimal and is not adequately visible to the humaneye.

FIG. 19 illustrates at 1900 a layout operation with a robotic totalstation 1905 having a focused laser pointer 1910 in accordance with someembodiments of the invention. The laser pointer 1910 is focused at 1915so as to produce a spot 1920 of optimal size on the target. The laserhas a large diameter (e.g., 40 mm) at the lens and is preferably of awavelength having high luminance (e.g., green). Auto-focusing allowsbringing the laser into focus at any desired range, so that it can befocused to a small spot size, e.g., 2 mm diameter at 20 m. An optimalspot size and good visibility of the spot are achieved.

FIG. 20 illustrates at 2000 a layout operation with a robotic totalstation 2005 having a focused laser pointer 2010 in accordance with someembodiments of the invention. In this example, the laser pointer 2010 isfocused at 2015 so as to produce a spot of optimal diameter on thetarget. The laser has a large diameter (e.g., 40 mm) at the lens and ispreferably of a wavelength having high luminance (e.g., green).Auto-focusing allows to bring the laser into focus at any desired range,so that it can be focused to a small spot size, e.g., 4 mm diameter at120 m. An optimal spot size and good visibility of the spot areachieved.

FIG. 4 schematically illustrates at 400 a layout scenario using a totalstation 405 with a focused laser pointer 415 to layout a point on aceiling 410 in accordance with some embodiments of the invention. Theangle beta between the ceiling 410 and the pointing-laser beam 415 isshown at 425. A pointing-laser beam of width d_b shown at 420 produces aspot of width d_w shown at 430 according to the relationd _(—) w=d _(—) b/sin(beta)so that d_w≈3·d_b for beta=20 deg and d_w≈6·d_b for beta=9 deg.

The advantage of the focused pointing-laser beam over the prior-artmethod using the unfocused EDM beam can be seen from comparison of FIG.4 with the prior-art scenario of FIG. 3.

FIG. 21 illustrates at 2100 a method of operating an apparatus to setout a point in accordance with some embodiments of the invention. Datarepresenting a target location is retrieved at 2105. The data can befrom a model, from a previous measurement of this apparatus, or from aprevious measurement of a different apparatus, for example. Range(distance) and direction (elevation & azimuth) from the instrumentcenter to the target location are calculated at 2110. The pointing drivesystem (e.g., 1535 of FIG. 15) is operated at 2115 to aim the pointingaxis (e.g., 1520 of FIG. 15) at the target location (e.g., 1570 of FIG.15). The focusing optics drive (e.g., 1550 of FIG. 15) is operated at2120 to focus the pointing-laser beam (e.g. 1570 of FIG. 15) to have apredetermined spot size at the target location. The pointing-lasersource 1525 is activated at 2125 to generate the pointing-laser beam(e.g., 1530 of FIG. 15).

The steps of FIG. 21 can be ordered differently if desired. For example,step 2125 can be performed to generate the laser beam before one or moreof the other steps. For example step 2120 can be performed to set thelaser optics as soon as the range is determined. For example, step 2115can be performed to aim the pointing axis as soon as the direction ofthe target location is determined. For example, step 2110 can beperformed to calculate range and direction as soon as the targetlocation data is available.

FIG. 22 illustrates at 2200 a method of operating an apparatus tomeasure a point in accordance with some embodiments of the invention.

The pointing drive system (e.g., 1535 of FIG. 15) is operated at 2205 toaim the pointing-laser beam in the general direction of a targetlocation. This can be done, for example, either by direct user input tothe processor or by tapping on the camera image displayed on atouch-screen display to provide approximate aiming information.

The approximate range (distance) between the target location and theinstrument center is determined at 2210. This can be computed from astored model or from a stored prior measurement of this apparatus oranother apparatus, or can be obtained by measuring the range using theEDM of this apparatus (e.g., 1585 of FIG. 15). At 2215 the focusingoptics (e.g., 1550 of FIG. 15) is operated to focus the pointing-laserbeam (e.g., 1530 of FIG. 15) to have a predetermined spot size at theapproximate range. The pointing-drive system (e.g., 1535 of FIG. 15) isoperated at 2220 to aim the measurement beam at the target location. TheEDM is operated at 2225 to measure a precise range from the instrumentcenter to the target location, and to determine elevation and azimuthfrom pointing-drive system. Data is stored at 2230 representing themeasurement of the target location.

Some embodiments provide for the pointing-laser beam to be availableonly when the apparatus is operated in a Direct Reflex (DR) mode ofoperation. Some embodiments provide for the EDM measurement laser to beon and the pointing laser to be off when the pointing axis is beingmoved. Some embodiments provide for the EDM measurement laser to be onand the pointing laser to be off when the EDM is making a distancemeasurement. Some embodiments provide for the EDM measurement laser tobe off and the pointing laser to be on when the pointing axis isstationary. Some embodiments provide for the EDM measurement laser to beon and the pointing laser to be off when the EDM is unable to measure adistance (e.g., pointed at the sky). Some embodiments provide for theEDM measurement laser and the pointing laser never to be onsimultaneously.

U.S. Pat. No. 8,031,332 describes a visual-layout procedure which can beimplemented with an apparatus embodying features of the presentinvention. Some embodiments provide for the pointing-laser beam to beavailable during visual layout only when the apparatus is operated in aDirect Reflex (DR) mode of operation. Some embodiments provide for theEDM measurement laser to be on and the pointing laser to be off when thepointing axis is being moved to aim the pointing axis toward a targetlocation during visual layout. Some embodiments provide for the EDMmeasurement laser to be off and the pointing laser to be on when thevisual layout routine is complete and the pointing axis is stationaryand aimed at a target location. Some embodiments provide for the EDMmeasurement laser and the pointing laser never to be on simultaneouslyduring visual layout.

U.S. Pat. No. 7,441,340 B2 describes error compensation methods forsurveying instruments. Such methods can be used with apparatus inaccordance with some embodiments of the present invention to calibrateand compensate collimation error of the pointing axis of the pointinglaser.

Some embodiments provide three ways of aiming: using a tracker, using afocusable laser pointer (e.g., green), and using the EDM measurementbeam (e.g., red) as a laser pointer. To ensure measurement accuracyregardless of which of these is used for aiming, some embodiments usethree separate sets of collimation error corrections, one for eachaiming device, and switches between these so that the appliedcollimation error correction is appropriate for the aiming device in inuse. The collimation error correction is used to adjust thepointing-direction control (e.g., 1540 in FIG. 15) so that theinstrument aims at the same target location regardless of whether thetracker, the laser point, the measurement beam is used, even thoughthese might otherwise result in a small discrepancy.

A traditional way to obtain the calibration-error corrections has been:

-   -   1. Calibrate the error compensator by obtaining a tilt reading        in a first direction, turning the instrument 180 degrees and        obtaining a tilt reading in a second direction, and calculating        the average of the tilt readings in the two directions. Any        deviation from zero is considered an error that has to be stored        for use as a zero point correction.    -   2. Perform a two-face measurement to a static target and        calculate the collimation error from the difference of the        angles in face one and face two.    -   3. Repeat step 2 for each aiming device separately.

Some embodiments in accordance with the present invention employ asimplified workflow to calibrate the aim of the two laser pointers(e.g., a fixed-focus red EDM laser used as a pointer and a focusablegreen pointing laser) and the compensator. This simplified workflowgives slightly lower accuracy but reduces the time required:

-   -   1. Aim the red laser pointer to a static target (mark on a wall,        etc) which gives face one, and register the horizontal angle        (HA), the vertical angle (VA), the tilt reading (TiltX, Tilt Y).    -   2. Switch to face two, aim the green laser pointer to the same        target, and register HA, VA, TiltX and TiltY.    -   3. Switch back to face one, aim the green laser pointer to the        target, and register HA and VA.    -   4. Calculate the compensator zero point from the average of the        tilt readings in face one and face two.    -   5. Calculate the collimation error of the green laser pointer        from the difference between the angle readings in face one and        face two. The vertical collimation error of the green laser        pointer will be affected by any errors in the calibration of the        compensator and is corrected with compensator zero point        resulting from the calculation in point 4.    -   6. Calculate the collimation error of the red laser pointer as        the collimation error of the green laser pointer added with the        angular difference between the red and green laser pointer in        face one.

The collimation error of the green laser pointer can be dependent on thedistance to the target. This can be caused by production tolerances andmisalignments of the optics or a nonlinear movement of the focusinglens. In some embodiments, these errors are handled by measuring thecollimation error on a set of different distances and storing theresults as a compensation table. This compensation table is consulted toobtain the appropriate collimation-error correction whenever theinstrument has measured or otherwise determined a distance to thetarget, and the pointing-direction control is adjusted accordingly. Insome embodiment, the same type of compensation for distance-dependentcollimation error is used for the tracker.

Those of ordinary skill in the art will realize that the detaileddescription of embodiments of the present invention is illustrative onlyand is not intended to be in any way limiting.

In the interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will beappreciated that in the development of any such actual implementation,numerous implementation-specific decisions must be made to achieve thedeveloper's specific goals, such as compliance with application- andbusiness-related constraints, and that these specific goals will varyfrom one implementation to another and from one developer to another.Moreover, it will be appreciated that such a development effort might becomplex and time-consuming, but would nevertheless be a routineundertaking of engineering for those of ordinary skill in the art havingthe benefit of this disclosure.

In accordance with embodiments of the present invention, the components,process steps and/or data structures may be implemented using varioustypes of operating systems (OS), computer platforms, firmware, computerprograms, computer languages and/or general-purpose machines. Themethods can be run as a programmed process running on processingcircuitry. The processing circuitry can take the form of numerouscombinations of processors and operating systems, or a stand-alonedevice. The processes can be implemented as instructions executed bysuch hardware, by hardware alone, or by any combination thereof. Thesoftware may be stored on a program storage device readable by amachine. Computational elements can be implemented using anobject-oriented programming language such that each required element isinstantiated as needed.

Those of skill in the art will recognize that devices of a lessgeneral-purpose nature, such as hardwired devices, field programmablelogic devices (FPLDs), including field programmable gate arrays (FPGAs)and complex programmable logic devices (CPLDs), application specificintegrated circuits (ASICs), or the like, may also be used withoutdeparting from the scope and spirit of the inventive concepts disclosedherein.

Methods in accordance with some embodiments may be implemented on a dataprocessing computer such as a personal computer, workstation computer,mainframe computer, or high-performance server running an OS such as aversion of Microsoft® Windows® available from Microsoft Corporation ofRedmond, Wash., or various versions of the Unix operating system such asLinux available from a number of vendors. The methods may also beimplemented on a multiple-processor system, or in a computingenvironment including various peripherals such as input devices, outputdevices, displays, pointing devices, memories, storage devices, mediainterfaces for transferring data to and from the processor(s), and thelike. Such a computer system or computing environment may be networkedlocally, or over the Internet.

Any of the above-described methods and their embodiments may beimplemented by means of a computer program. The computer program may beloaded in an apparatus having a processor, such as a robotic totalstation. Therefore, the invention also relates to a computer programwhich can enable a processor to carry out any one of the describedmethods and their embodiments.

The invention also relates to a computer-readable medium or acomputer-program product including the above-mentioned computer program.The computer-readable medium or computer-program product may forinstance be a magnetic tape, an optical memory disk, a magnetic disk, amagneto-optical disk, a CD ROM, a DVD, a CD, a flash memory unit or thelike, wherein the computer program is permanently or temporarily stored.The invention also relates to a computer-readable medium (or to acomputer-program product) having computer-executable instructions forcarrying out any one of the methods of the invention.

The invention also relates to a firmware update adapted to be installedon devices already in the field, i.e. a computer program which isdelivered to the field as a computer program product.

The constituent parts of a unit may be distributed in different softwareor hardware components or devices for bringing about the intendedfunction.

Furthermore, the units may be gathered together for performing theirfunctions by means of a combined, single unit.

The following is a partial summary of inventive concepts describedherein:

-   -   1. A robotic laser-pointing apparatus, comprising:        -   a. an instrument center,        -   b. a first rotation axis, a second rotation axis, and a            pointing axis, having a known relationship to an instrument            center,        -   c. a laser source providing a pointing-laser beam along the            pointing axis,        -   d. a pointing drive system to aim the laser beam by rotating            the pointing axis about the instrument center in response to            a pointing-direction control,        -   e. focusing optics having a focusing-optics drive to focus            the pointing-laser beam in response to a focusing-optics            control,        -   f. a processor, responsive to target-position information,            to generate the pointing-direction control and the            focusing-optics control.    -   2. The apparatus of 1, wherein at least two of the first        rotation axis, the second rotation axis, and the pointing axis        intersect at the instrument center.    -   3. The apparatus of 1 or 2, wherein the target-position        information represents a target location relative to the        instrument center, and the pointing-direction control causes the        pointing drive system to aim the pointing-laser beam at the        target location.    -   4. The apparatus of 3, wherein the focusing-optics control        causes the focusing optics to focus the pointing-laser beam with        a predetermined beam diameter at the target location.    -   5. The apparatus of 4, wherein the processor is operative to        compute the focusing-optics control based on range between the        instrument center and the target location.    -   6. The apparatus of one of 1-5, wherein the pointing drive        system comprises a first controllable drive for rotating the        pointing axis to a selected rotation angle about the first        rotation axis, and a second controllable drive for rotating the        pointing axis to a selected rotation angle about the second        rotation axis, and wherein the pointing-direction control        comprises signals representing the selected rotation angles.    -   7. The apparatus of one of 1-6, wherein the focusing optics        system comprises at least one optical element and wherein the        focusing-optics drive is operative to focus the pointing-laser        beam by modifying at least one optical property of the focusing        optics.    -   8. The apparatus of one of 1-7, wherein the focusing optics        system comprises a collimation lens having an exit aperture of        at least 5 mm.    -   9. The apparatus of one of 1-7, wherein the focusing optics        system comprises a collimation lens having an exit aperture of        at least 10 mm.    -   10. The apparatus of one of 1-7, wherein the focusing optics        system comprises a collimation lens having an exit aperture of        at least 20 mm.    -   11. The apparatus of one of 1-7, wherein the focusing optics        system comprises a collimation lens having an exit aperture of        at least 30 mm.    -   12. The apparatus of one of 1-11, wherein the processor is        further operative to compensate the pointing-direction control        for any lack of mutual orthogonality of the first rotation axis        and the second rotation axis.    -   13. The apparatus of one of 1-12, wherein the processor is        further operative to compensate the pointing-direction control        for any lack of mutual orthogonality of the second rotation axis        and the pointing axis.    -   14. The apparatus of one of 1-13, further comprising an        electronic distance measurement system which emits a measurement        beam along a measurement-beam path, and the pointing drive        system is operative to aim the measurement beam by rotating the        measurement-beam path about the instrument center in response to        the pointing-direction control.    -   15. The apparatus of 14, wherein the measurement-beam path        intersects the instrument center.    -   16. The apparatus of one of 14-15, wherein the processor is        further operative to compensate the pointing-direction control        for at least one of parallax and divergence of the pointing axis        with respect to the measurement-beam path.    -   17. The apparatus of one of 14-16, wherein the electronic        distance measurement system comprises a measurement-beam source,        and wherein the laser source and the measurement-beam source are        operated alternately.    -   18. The apparatus of one of 14-16, wherein the processor is        operative to correct for misalignment between the pointing axis        and the measurement-beam path by applying a first correction to        the pointing-direction control when the pointing-laser beam is        being aimed and by applying a second correction to the        pointing-direction control when the measurement beam is being        aimed.    -   19. The apparatus of one of 14-16, wherein the electronic        distance measurement system employs the laser source for        electronic distance measurement.    -   20. The apparatus of one of 1-19, wherein the pointing-laser        beam is a class 2 laser beam.    -   21. The apparatus of one of 1-20, wherein the pointing-laser        beam has a wavelength within a range visible to the human eye.    -   22. The apparatus of one of 1-21, wherein the pointing laser        beam has a wavelength of between 500 nm and 610 nm.    -   23. The apparatus of one of 1-21, wherein the pointing laser        beam has a wavelength of between 450 nm and 550 nm.    -   24. The apparatus of one of 1-21, wherein the pointing laser        beam has a wavelength of between 520 nm and 590 nm.    -   25. The apparatus of one of 1-24, wherein the processor is        operative to control the laser source to set a power level of        the pointing-laser beam between a zero level and a maximum        level.    -   26. The apparatus of one of 1-25, further comprising a camera        operative to capture at least one of a still image and a live        video image of a target region.    -   27. The apparatus of 26, wherein the camera has a field of view        which encompasses a segment of the pointing axis.    -   28. The apparatus of one of 26-27, further comprising a        touch-screen display which is operative to display an image of a        target region captured by the camera, and wherein the processor        is operative to generate the pointing-direction control in        response to a tap at a point on the touch-screen display        corresponding to a target location such that the pointing drive        system aims the pointing axis at the target location.    -   29. The apparatus of 28, wherein the camera is calibrated such        that a pixel position in a camera image on the touch-screen        display which corresponds to a spot of the laser beam is        calibrated for different distances between 1 m and 100 m to        facilitate tap and move navigation using the camera image.    -   30. The apparatus of one of 26-29, wherein the camera comprises        an automatic exposure control which indicates an exposure level,        and the processor is operative to use the indicated exposure        level to adjust output power of the laser source.    -   31. The apparatus of one of 1-30, further comprising a remote        controller and a data link enabling communication between the        remote controller and the processor.    -   32. The apparatus of 31, wherein the remote controller comprises        a touch-screen display, and the processor is operative to        control operation of the apparatus in response to commands        entered on the touch-screen display.    -   33. The apparatus of 32, wherein the remote controller is        operative to control the laser source, the pointing drive system        and the focusing optics via the data link.    -   34. The apparatus of 32, wherein the remote controller is        operative to retrieve an image captured by the camera.    -   35. The apparatus of one of 1-34, wherein the processor is        further operative to determine a collimation-error correction by        performing a calibration procedure.    -   36. The apparatus of one of 1-35, wherein the processor is        further operative to retrieve a collimation-error correction        from a set of stored correction data.    -   37. The apparatus of one of 1-36, wherein the target position        information is a stored representation of a target location.    -   38. The apparatus of one of 1-36, wherein the target position        information is obtained from a stored model having a known        relationship to the instrument center.    -   39. The apparatus of one of 1-36, wherein the target position        information is a stored representation of a measured point        having a known relationship to the instrument center.    -   40. The apparatus of one of 1-39, further comprising a        diffraction element positioned along the pointing axis to        diffract the pointing-laser beam such that a spot focused on a        target has at least one of a crosshair shape and a darkened        center region.    -   41. The apparatus of one of 1-40, further comprising a leveling        device operative to bring the first rotation axis parallel to        plumb (gravity vector).    -   42. The apparatus of one of 1-40, further comprising a tilt        sensor operative to measure deviation of the first rotation axis        of the robot to plumb and wherein the processor is operative to        adjust the pointing-direction control to compensate for the        measured deviation.    -   43. A method of operating an apparatus according to one of 1-42,        comprising:        -   i. retrieving data representing a target location,        -   ii. calculating distance and direction from the instrument            center to the target location,        -   iii. operating the pointing drive system to aim the pointing            axis at the target location,        -   iv. operating the focusing optics to focus the            pointing-laser beam to a target distance based on the target            location, [Note: the “target distance” can be different than            the target location so the spot size is optimized at the            target location]        -   v. operating the laser source to provide the pointing-laser            beam focused at the target distance.    -   44. A method of operating an apparatus according to one of        14-42, comprising:        -   i. operating the pointing drive system to aim the            pointing-laser beam in the general direction of a target            location,        -   ii. determining a range between the target location and the            instrument center,        -   iii. operating the focusing optics to focus the            pointing-laser beam to have a predetermined spot size at the            range,        -   iv. operating the pointing drive system to aim the            measurement beam at the target location,        -   v. operating the EDM to measure range from the instrument            center to the target location,        -   vi. storing data representing a measurement of the target            location.

The invention claimed is:
 1. A robotic laser-pointing apparatus,comprising: a. an instrument center, b. a first rotation axis, a secondrotation axis, and a pointing axis, having a known relationship to theinstrument center, c. a laser source providing a pointing-laser beamalong the pointing axis toward a target, d. a pointing drive system toaim the pointing-laser beam by rotating the pointing axis about theinstrument center in response to a pointing-direction control, e.focusing optics having a focusing-optics drive to focus thepointing-laser beam in response to a focusing-optics control, f. ameasurement laser source providing a measurement beam along ameasurement-beam path, g. a prism positioned along the pointing axis andconfigured to direct at least a portion of the measurement beam alongthe pointing axis and toward the target, and h. a processor, responsiveto light from the measurement beam reflected from the target, togenerate the focusing-optics control.
 2. The apparatus of claim 1,wherein at least two of the first rotation axis, the second rotationaxis, and the pointing axis intersect at the instrument center.
 3. Theapparatus of claim 1, wherein the processor is further responsive totarget-position information, to generate the pointing-direction control,the target-position information representing a target location relativeto the instrument center, and the pointing-direction control causing thepointing drive system to aim the pointing-laser beam at the targetlocation.
 4. The apparatus of claim 3, wherein the focusing-opticscontrol causes the focusing optics to focus the pointing-laser beam witha predetermined beam diameter at the target location.
 5. The apparatusof claim 4, wherein the processor is operative to compute thefocusing-optics control based on range between the instrument center andthe target location.
 6. The apparatus of claim 3, wherein the targetposition information is a stored representation of a target location. 7.The apparatus of claim 3, wherein the target position information isobtained from a stored model having a known relationship to theinstrument center.
 8. The apparatus of claim 3, wherein the targetposition information is a stored representation of a measured pointhaving a known relationship to the instrument center.
 9. The apparatusof claim 1, wherein the pointing drive system comprises a firstcontrollable drive for rotating the pointing axis to a selected rotationangle about the first rotation axis, and a second controllable drive forrotating the pointing axis to a selected rotation angle about the secondrotation axis, and wherein the pointing-direction control comprisessignals representing the selected rotation angles.
 10. The apparatus ofclaim 1, wherein the focusing optics comprises at least one opticalelement and wherein the focusing-optics drive is operative to focus thepointing-laser beam by modifying at least one optical property of thefocusing optics.
 11. The apparatus of claim 1, wherein the focusingoptics comprises a collimation lens having an exit aperture of at least5 mm.
 12. The apparatus of claim 1, wherein the focusing opticscomprises a collimation lens having an exit aperture of at least 10 mm.13. The apparatus of claim 1, wherein the focusing optics comprises acollimation lens having an exit aperture of at least 20 mm.
 14. Theapparatus of claim 1, wherein the focusing optics comprises acollimation lens having an exit aperture of at least 30 mm.
 15. Theapparatus of claim 1, wherein the processor is further operative tocompensate the pointing-direction control for any lack of mutualorthogonality of the first rotation axis and the second rotation axis.16. The apparatus of claim 1, wherein the processor is further operativeto compensate the pointing-direction control for any lack of mutualorthogonality of the second rotation axis and the pointing axis.
 17. Theapparatus of claim 1, wherein the pointing drive system is operative toaim the measurement beam by rotating the measurement-beam path about theinstrument center in response to the pointing-direction control.
 18. Theapparatus of claim 17, wherein the processor is further operative tocompensate the pointing-direction control for at least one of parallaxand divergence of the pointing axis with respect to the measurement-beampath.
 19. The apparatus of claim 17, wherein the processor is operativeto correct for misalignment between the pointing axis and themeasurement-beam path by applying a first correction to thepointing-direction control when the pointing-laser beam is being aimedand by applying a second correction to the pointing-direction controlwhen the measurement beam is being aimed.
 20. A method of operating anapparatus according to claim 17, comprising: i. operating the pointingdrive system to aim the pointing-laser beam in the general direction ofa target location, ii. determining a first range between the targetlocation and the instrument center, iii. operating the focusing opticsto focus the pointing-laser beam to have a predetermined spot size atthe range, iv. operating the pointing drive system to aim thepointing-laser beam at the target location, v. determining a secondrange between the target location and the instrument center, vi. storingdata representing a measurement of the target location.
 21. Theapparatus of claim 1, wherein the measurement-beam path intersects theinstrument center.
 22. The apparatus of claim 1, wherein the lasersource and the measurement-beam source are operated alternately.
 23. Theapparatus of claim 1, wherein an electronic distance measurement systememploys the measurement laser source for electronic distancemeasurement.
 24. The apparatus of claim 1, wherein the pointing-laserbeam is a class 2 laser beam.
 25. The apparatus of claim 1, wherein thepointing-laser beam has a wavelength within a range visible to the humaneye.
 26. The apparatus of claim 1, wherein the pointing laser beam has awavelength of between 500 nm and 610 nm.
 27. The apparatus of claim 1,wherein the pointing laser beam has a wavelength of between 450 nm and550 nm.
 28. The apparatus of claim 1, wherein the pointing laser beamhas a wavelength of between 520 nm and 590 nm.
 29. The apparatus ofclaim 1, wherein the processor is operative to control the laser sourceto set a power level of the pointing-laser beam between a zero level anda maximum level.
 30. The apparatus of claim 1, further comprising acamera operative to capture at least one of a still image and a livevideo image of a target region.
 31. The apparatus of claim 30, whereinthe camera has a field of view which encompasses a segment of thepointing axis.
 32. The apparatus of claim 30, further comprising atouch-screen display which is operative to display an image of a targetregion captured by the camera, and wherein the processor is operative togenerate the pointing-direction control in response to a tap at a pointon the touch-screen display corresponding to a target location such thatthe pointing drive system aims the pointing axis at the target location.33. The apparatus of claim 32, wherein the camera is calibrated suchthat a pixel position in a camera image on the touch-screen displaywhich corresponds to a spot of the laser beam is calibrated fordifferent distances between 1 m and 100 m to facilitate tap and movenavigation using the camera image.
 34. The apparatus of claim 30,wherein the camera comprises an automatic exposure control whichindicates an exposure level, and the processor is operative to use theindicated exposure level to adjust output power of the laser source. 35.The apparatus of claim 1, further comprising a remote controller and adata link enabling communication between the remote controller and theprocessor.
 36. The apparatus of claim 35, wherein the remote controllercomprises a touch-screen display, and the processor is operative tocontrol operation of the apparatus in response to commands entered onthe touch-screen display.
 37. The apparatus of claim 36, wherein theremote controller is operative to control the laser source, the pointingdrive system and the focusing optics via the data link.
 38. Theapparatus of claim 36, wherein the remote controller is operative toretrieve an image captured by a camera.
 39. The apparatus of claim 1,wherein the processor is further operative to determine acollimation-error correction by performing a calibration procedure. 40.The apparatus of claim 1, wherein the processor is further operative toretrieve a collimation-error correction from a set of stored correctiondata.
 41. The apparatus of claim 1, wherein the prism diffracts thepointing-laser beam such that a spot focused on a target has at leastone of a crosshair shape and a darkened center region.
 42. The apparatusof claim 1, further comprising a leveling device operative to bring thefirst rotation axis parallel to plumb.
 43. The apparatus of claim 1,further comprising a tilt sensor operative to measure deviation of thefirst rotation axis of the robot to plumb and wherein the processor isoperative to adjust the pointing-direction control to compensate for themeasured deviation.
 44. A method of operating an apparatus according toclaim 1, comprising: i. retrieving data representing a target location,ii. calculating distance and direction from the instrument center to thetarget location, iii. operating the pointing drive system to aim thepointing axis at the target location, iv. operating the focusing opticsto focus the pointing-laser beam to a target distance based on thetarget location, v. operating the laser source to provide thepointing-laser beam focused at the target distance.